Developing An Open Source Bike Computer

While bicycles appear to have standardized around a relatively common shape and size, parts for these bikes are another story entirely. It seems as though most reputable bike manufacturers are currently racing against each other to see who can include the most planned obsolescence and force their customers to upgrade even when their old bikes might otherwise be perfectly fine. Luckily, the magic of open source components could solve some of this issue, and this open-source bike computer is something you’ll never have to worry about being forced to upgrade.

The build is based around a Raspberry Pi Zero in order to keep it compact, and it uses a small 2.7 inch LCD screen to display some common information about the current bike ride, including location, speed, and power input from the pedals. It also includes some I2C sensors including pressure and temperature as well as an accelerometer. The system can also be configured to display a map of the current ride as well thanks to the GPS equipment housed inside. It keeps a log in a .fit file format as well so that all rides can be archived.

When compared against a commercial offering it seems to hold up pretty well, and we especially like that it’s not behind a walled garden like other products which could, at any point, decide to charge for map upgrades (or not offer them at all). It’s a little more work to set up, of course, but worth it in the end. It might also be a good idea to pair it with other open source bicycle components as well.

Thanks to [Richard] for the tip!

Smart Camera Based On Google Coral

As machine learning and artificial intelligence becomes more widespread, so do the number of platforms available for anyone looking to experiment with the technology. Much like the single board computer revolution of the last ten years, we’re currently seeing a similar revolution with the number of platforms available for machine learning. One of those is Google Coral, a set of hardware specifically designed to take advantage of this new technology. It’s missing support to work with certain hardware though, so [Ricardo] set out to get one working with a Raspberry Pi Zero with this smart camera build based around Google Coral.

The project uses a Google Coral Edge TPU with a USB accelerator as the basis for the machine learning. A complete image for the Pi Zero is available which sets most of the system up right away including headless operation and includes a host of machine learning software such as OpenCV and pytesseract. By pairing a camera to the Edge TPU and the Raspberry Pi, [Ricardo] demonstrates many of its machine learning capabilities with several example projects such as an automatic license plate detector and even a mode which can recognize whether or not a face mask is being worn, and even how correctly it is being worn.

For those who want to get into machine learning and artificial intelligence, this is a great introductory project since the cost to entry is so low using these pieces of hardware. All of the project code and examples are available on [Ricardo]’s GitHub page too. We could even imagine his license plate recognition software being used to augment this license plate reader which uses a much more powerful camera.

Retro Console Upgrade Gives Atari Flair

If you’re desperate for a sense of nostalgia for video games of yore but don’t want to shell out the big bucks for an NES classic, you can always grab a single arcade-style game that’ll plug straight into your TV. Of course it’s no longer 1980, and playing Space Invaders or Asteroids can get old after a while. When that happens, just replace the internals for an upgraded retro Atari 2600 with all the games from that system instead of just one.

As expected for something that has to fit in such a tiny package, this upgrade is based on a Raspberry Pi Zero. It’s not quite as simple as throwing RetroPi on it and calling it a day, though. For one, [Blue Okiris] is still using the original two-button controller/joystick that came with the Ms. Pac-Man game this build is based on, and that added its own set of challenges. For another, RetroPi didn’t have everything he needed so he switched to another OS called Recalbox. It also includes Kodi so it could be used as a media center as well.

The build looks like a hack in the truest sense of the word. The circuit board sticks out the bottom a little bit, but this is more of a feature than a bug because that’s where some extra buttons and the power switch are. Overall, it’s a great Retro Atari system that has all the true classics that should keep [Blue Okiris] entertained until Atari releases an official system one day. If you’d like to go a little deeper in the Atari world, though, you could always restore one instead.

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PiPod: A Raspberry Pi Zero Portable Music Player

[Bram] wasn’t satisfied with the portable music playback devices that were currently available. He craved an offline music player that had a large storage capacity but found that this was only available in high-end, off-the-shelf options, which were far too expensive. [Bram] decided to make his own, powered by a Raspberry Pi zero. After building an initial prototype, the design was iterated a few times, with the latest version featuring a BOM cost of roughly €80.

The whole project is open source, with hardware and software files available on the project GitHub. A 2.2″ TFT displays the UI, which is of course completely customisable. Everything is squashed into a 3D printed case, which has the smallest form factor possible whilst retaining a decent amount of battery life. The electronics are what you’d expect: a boost converter to produce 5 V for the Pi from the 3.7V battery, a charge controller and a battery protection circuit. As a bonus, the battery voltage is monitored with a 12-bit ADC which reports to the Pi, enabling it to do a safe shutdown at low voltage, and display battery level on the UI.

Since the whole purpose of the device is to play audio, onboard filtered PWM wasn’t going to cut it, so instead a 24-bit DAC talks to the Pi via I2S. The audio player backend is VLC, so there’s support for plenty of different file types. A disc image of the whole system is available with everything pre-configured, and you can even buy the assembled PCB from Tindie.

Want to keep the look and feel of your old iPod? We covered an impressive restoration of a 6th gen model, upgrading the storage and battery significantly.

Old Modem, New Internet.

Do you remember the screeching of a dial-up modem as it connected to the internet? Do you miss it? Probably not, but [Erick Truter] — inspired by a forum post and a few suggestions later — turned a classic modem into a 3G Wi-Fi hotspot with the ubiquitous Raspberry Pi Zero.

Sourcing an old USRobotics USB modem — allegedly in ‘working’ condition — he proceeded to strip the modem board of many of its components to make room for the new electronic guts. [Truter] found that for him the Raspberry Pi Zero W struggled to maintain a reliable network, and so went with a standard Pi Zero and a USB  Wi-Fi dongle dongle. He also dismantled a USB hub to compensate for the Zero’s single port. Now,  to rebuild the modem — better, faster, and for the 21st century.

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Putting The Pi In Piano

Working on a PhD in composition, [Stephen Coyle] spends a fair bit of time at his electric keyboard. Setting himself up to work can be a bit of a task, so he felt he could improve the process and make it easy as Pi.

Finding it an odious task indeed to use notation software, connecting his laptop to his keyboard is a must — avoiding a warren of wires in the move is a similar priority. And, what if he could take advantage of the iPad’s unique offerings too? Well, a Raspberry Pi Zero W running Ravelox — an RTP MIDI protocol — makes  his music available on his network to record on whichever device he pleases.

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Remote Controlled Streaming Speakers

For want of a better use of a spare Raspberry Pi Zero W and a set of LogitechZ-680 surround sound speakers, [Andre van Kammen] hacked them together to make them stream music playing from his phone.

It was stumbling across the Pi Music Box distribution that really got the ball rolling, and the purchase of a pHAT DAC laid the foundation. Cracking open the speakers’ controller case, [Kammen] was able to get 5V of power off some terminals even when the speakers were on standby — awesome! — which the Pi could use. Power and volume are controlled via the Pi’s GPIO pins with a diode to drop the voltage and prevent shorts.

Now, how to tell whether the speakers are on or off? Well, a pin on the display connector changes to 4.3V when it’s on, so wiring a 10k resistor and a diode to said pin is a hackable solution. Finishing off the wired connections, it proved possible to cram the pHAT DAC inside the controller case with the GPIO header sticking out the back to mount the Pi upon with no other external wires — double awesome!

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